You need to check with your US INSURANCE broker.
There are 4 distinct processes that you have to account for
1. FEDERAL importation of your car. the FEDS (not the states) allow temporary importation of your automobile if you are planning to be in US for less than one year. This is NOT formal importation, which requires a manufacturer's letter and NTHSA compliance. Formal importation is required if you want to dispose of your car in US.
2. State registration/plating of your car. This varies from state to state. Some require federal importation, some don't. Some require registration within 10 days of arrival in the state (regardless of temporary visa status), some don't care.
3. Driver's license. Again, varies from state to state. All require you to get a state DL at some point. Some will take into account previous provincial DL to avoid need for driving exam. Some will take your Cdn DL in exchange for new state DL, some let you keep your old one. Most states now require SSN (or letter from SSA stating you are not entitled to SSN) to get DL. Some TD spouses have been shut out of DL for lack of SSA (IL, NJ come to mind).
4. Insuring your car. Most Cdn insurers will not cover you once you MOVE to US. Some will cover you if you convince them that you are in US temporarily, but you MUST notify them that you are going to be living in US. Some US insurers will insure your care even with Cdn plates, but will likely insist that the situation be rectified be renewal time (six months). Rates may not be that good for what they consider new drivers. Remember too, that without formally importing your ar, you will not be able to signover the car if you wreck it.
The ideal situation, even if you are absolutely sure that you are going to be in US for 1 year or less on TN is to (1) import your car formally on the way down. (2) Co-ordicate your insuarnce coverage, leaving your Cdn one and getting US one. (3-4) Based on the requirements of the Insuarance company and the local DMV regs, plate your car and get DL as soon as you can.
The goal is to avoid prolonged driving in US with Cdn DL, Cdn plates and/or Cdn insurance.